How to Choose a Cordless Telephone

by editor@text4price.com @ 12 July 2006 - 15:12:10

First invented by Teri Pall in 1965, cordless telephones have become common place today. The first cordless telephones used the 1.7 MHz frequency. Today, cordless telephones come in four frequencies: 49 MHz, 900 MHz, 2.4 GHz, and 5.8 GHz. However, is choosing the highest frequency the best way to go about buying a cordless telephone?

The earliest cordless telephones at 27 MHz were affected by poor sound quality and security and had limited range. Even when the 49 MHz phones came out, poor sound quality and eavesdropping continued to be an issue. It was possible for someone in range to pick up on the conversation using a radio scanner. Many baby monitors were also capable of picking up conversations from a 49 MHz cordless phone.

With the introduction of digital spread spectrum technology in 1995, it became more difficult to eavesdrop. This technology uses frequency hopping to spread the audio signal over a larger bandwidth. While the digital 900 MHz, 2.4 GHz, and 5.8 GHz phones incorporate this technology to provide greater security, the 2.4 GHz and 5.8 GHz phones also fall out of range of detection of most radio scanners, making it really difficult for someone to eavesdrop on your conversation.

The 2.4 GHz and 5.8 GHz phones also improved the distance of using a cordless phone from the base. For instance, the Sony SPP-S2730 claims its cordless handsets can be used as walkie talkies up to 600 feet. In general, 900 MHz with spread spectrum cordless phone has a range of 200-1500 feet whereas its 2.4 and 5.8 GHz counterparts are closer to 300 to 2000 feet.

The 900 MHz phones are the most common cordless phones in use today. The 900 MHz and 2.4 GHz band are also being used by other devices such as Bluetooth, wireless LAN, and microwaves. So while the 2.4 GHz maybe a secure phone, it is also more prone to interference if the devices mentioned are in close proximity. The 5.8 GHz telephones on the other hand are less prone to interference as they are mostly used in military communications. Your microwave and wLAN will not interfere with it. However, it also requires more power and may drain battery life quicker than a 2.4 GHz phone.

The size of the antenna on the phone is also inversely proportional to the frequency; the higher frequency phones needing a smaller antenna and the lower frequency phones having a larger one.

So which one is the right one for you? The most common cordless phone in use today is at 900 MHz; however the 2.4 GHz provides more privacy but could increase interference if devices such as wLAN or microwaves are in use in your home or office. In which case, the 5.8 GHz may be a better option but the drawback of potentially shortening battery life could be an expensive option. In the end which pone to buy will depend upon what you are willing to live with: less privacy (900 MHz), more interference (2.4 GHz), or shorter battery life (5.8 GHz).

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Filed under: Phones

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